Did Earth's Continents Come from Space?

Earth didn't always have the land beneath your feet, but what might have caused it to form is a bit of a mystery.

Hosted by: Savannah Geary (they/them)
----------
Huge thanks go to the following Patreon supporter for helping us keep SciShow Space free for everyone forever: Jason A Saslow, David Brooks, and AndyGneiss!

----------
Looking for SciShow elsewhere on the internet?
----------
Sources

Images

[TheDanEdwards]

Looking at the comments so far it seems many people don't understand the problem (and it was not presented as well here as it could have been.) The difficult problem to understand is how did Earth's crust originally differentiated. Less dense minerals in continents today is taken as a given, but initially the crust would have been more uniform. There are hypotheses on how the first continents arose, and meteor impacts is one of them.

[argentpuck]

Accidentally heard "non-avian dinosaurs" as "non-alien." Gonna stick with the error, though, it's more fun to imagine there were extraterrestrial diplodocuses.

[DemPilafian]

I love these science videos that take us on a detective's journey of piecing together overlapping clues from different disciplines (in this case chemistry, geology, and astronomy) to unravel the mysteries of the past. Very cool! 👍

[davetoms]

This video had quite an _impact_ on my understanding of our Earth's history.
...I'll see myself out 😅

[adamwishneusky]

Thank you for this science! I’ve been struggling to get continents to form on the planet I’m terraforming

[eppiox]

anyone else thing the waterfall at 4:03 was really cool looking?

[baarni]

A perfect example of land rafting is in the crater of Kilauea. When there was a water lake at the bottom and it began erupting in December 2020 the water was boiled away by the lava but it also cooled and solidified a large slab that was about 20 metres high. The crater then filled with lava and rose some 1600 feet but the slab of water cooled lava still remains floating on the current lava lake. Earths land masses most likely are the result of a similar process.

[Unifrog_]

All this time I was taking continental drift for granite.

[DoctorX]

Hi new person! Good job presenting, hope to see you again!

[christopherminto]

Could Thea’s impact have contributed? I’was watching a video where the theory was it vaporised the outer layers of the earth turning earth into a synestia.

[harrietharlow]

This is a very interesting hypothesis. I'd never thought of this before, but it does make sense. The timing is certainly correct.

[TheJamesRedwood]

0:59 this is NOT an example of granitic structures floating above basaltic ones. You have shown a volcano - i.e. a basaltic structure, rising from an oceanic plate.

[JDSleeper]

Sounds like the Late Heavy Bombardment was the cause?

[gonebabygone]

Where is the waterfall that appears at 4:02?

[evanrigel]

even though it's (probably) incorrect, i can't help feeling like this conversation was started by a scientist trying to explain tectonics to a toddler
"why are there continents?"
some bits of rock are lighter so they float
"why?"
cause theyre made of a different rock, granite
"but where did they come from?"
deep inside the earth
"but where did /that/ come from?"
hmmmm. good question kid.

[MaxContagion]

"more then one paper". or in some cases a call from a outside source to get their heads out of there butts. even after overwhelming evidence was found contradicting previous findings

[GerardBendotti]

It's Western Australia. WA is a state of Australia on the western side of the country

[Sizifus]

Never been a geology buff, but this is interesting. One more to the list of happenings to set the conditions for the rise of life on Earth. That said, what about Earth's impact with the heavenly body that caused the Moon to form, wouldn't that have kickstarted the continent cycle or was that way too early for the cycle to form?

[jeffreyknutson]

Savannah was AWESOME!!! Have her host more!!

[AnmAtAnm]

The hypothetical Theia impact that formed the moon was obviously powerful enough to break through the mantle. Is that too early to align with this continental formation theory?